Manufacture of thiohydroxy organic compounds



Patented Oct. 6, 1931 warren STATES PATENT oreics WILLIAM J". HALE, 0F MIDLAND, MICHIGAN, ASSIG-NOIR TO THE DOW CHEMICAL COM- PANY, CF MIDLAND, MICHIGAN, A CORPORATION OF MICHIGAN MANUFACTURE OF THIOHYDROXY ORGANIC COMPOUNDS No Drawing.

The present invention relates to processes for the manufacture of thiohydroxy organic compounds, and more particularly to the control of such processes whereby the formation of secondary products is prevented or repressed, and the reaction is directed substantially to the formation of the principal product in maximum yield.

It is well known that the action of water upon organic halides, and other organic derivatives of inorganic acids capable of hydrolysis, leads not only to the formation of primary substituted derivatives of the water type, known as hydroxides, alcohols, or phenols, but also, by dehydration of such primary compounds, to the formation of secondary substituted derivatives of the water type, known as oxides or ethers. Between such primary compound and the corresponding secondary derivative there is a tendency toward a condition of equilibrium as shown by the V following-equation where Rrepresents a univalent hydrocarbon radical:

- (1) 2ROH2R O+H O The well-known water tvpe of organic compound may be described as one wherein the molecule of water as a base undergoes a substitutionof one or both of itshydroa'en atoms by imivalent organic radicals: derivatives of water represented by replacement of the h drogen bv radicals higher valence than one, however, are not strictly clas ified as of the water type. When the oxygen of such water type compound is replaced bysuh phur, the hydrogen sulphide analog of the water type of organic compound is obtained. Under this h ad are included thiohvdroxides, or merca-ptans, and sulphides. orthioethers, which compounds in their reaction offormation are subject to a similar condition of equilibrium the hydroxides and ethers aforementioned, viz

2 2asnenzs+nzs Such types of analogous reactions. leading to the formation of derivatives of hvdrogen sulphide corresponding to those of the water type, are described as thiohydrolysis andde-' thiohydration, respectively.

invention, such disclosed means constituting,

Application filed. September 4, 1928. Serial No. 303,957.

I have discovered that, in any given organic chemical reaction wherein one of the primary. products gives rise to one or more secondary organic compounds existing in equilibrium therewith, it is feasibleto direct such reaction entirely to the preparation of the primary product by artificially establishing and maintaining within the system such concentration of secondary derivatives as is found to be formed under the conditions of the reaction.

To the accomplishment of the foregoing and related ends the invention, then, consists of the steps hereinafter fully described and particularly pointed out in the claims, the following description illustrating and setting forth in detail certain steps embodying the however, but several of the ways in which the principle of the invention may be used. 7

In the thiohvdrolvsis of chlorobenzene by pydrogen sulphide the equations are as folows:

The dethiohydration of the mercantan, CJLSH, yields the thioether, (Cd-1 b8, as the secondary substituted derivative of hydrogen sulphide, and such process is in eouilibrium with the reverse process of thiohydr'ation of the thioether into mercaptan. The reactions in question attain considerable proportions atabout 200 to 250 C. The relative concentration of the component factors in the equilibrium determines the direction of the reaction. It would be possible, in

accordance with the law of mass action,to conduct the thiohydrolysis of chlorobenzene in the presence of a qreatexcess of hydrogen sulphide. so that the forward direction of the equilibrium equation above would be repressed with the result that very little diphenyl sulphide could be formed. Such procedure. however, even where the handling of great excess of hydrogen sulphide is practical, cannot altogether prevent the formation of some diphenyl sulphide and especially so at the elevated temperatures most favorable for the primary reaction. In so far'as some diphenyl sulphide is formed, the yield autoclave capable of withstanding pressure of primary product is to such extent reduced. as high as 3,000 pounds per square inch, or It is simpler and more practical to set up more. Approximately 10 per cent of diinitially in the reaction system such concenphenyl sulphide and 3 per cent of diphenyl 5 tration of the secondary compound as correoxide, both figured on the basis of chloros ends to the equilibrium by the addition benzene used, are added, such amounts of the tiiereof in like amount to the reacting ingrclast two named compounds having been deterdients at the beginning of the reaction. In the mined in a previous run as being formed present instance. the equilibrium proportion under the conditions of the reaction. This ofdiphenyl sulphide is added initially to the mixture is then saturated with hydrogen sul- 75 reaction mixture. The further formation of phide, introduced under a moderate pressure, diphenyl sulphide at the expense of the prii. e.. between one and two atmospheres. The mary product, phenyl mcrcaptan, is thereby temperature is thereupon gradually increased repressed, and the thiohydrolysis of the to approximately 250 (1, and maintainedtor chlorobenzene leads solely to the production 2 to 3 hours. After cooling and release of so ofiphenyl mercaptan. pressure, the reaction mass is separated from Thiohydrolytic reactions maybe conducted the oily layer containing diphenyl sulphide inzanhydrous media, such as alcohol. It is and diphenyl oxide, which is returned to a possible, and often froma practicalstandsucceeding reaction. The aqueous portion,

- point preferable, however, to conduct such consisting of a solution of salts of thiophcnol operations in aqueous media under suitable and phenol, is acidulated and the latter comconditions. In such case where water is pounds distilled oil with steam. The crude resent, there will exist the two sets of equiproduct is then driedand tractionally dis- 'bria shown in equations (1) and (2) reptilled to separate the pure product-s. resenting the simultaneous operation of the In a continuous process the diphenyl sulprocesses of hydrolysis and thiohydrolysis. phide and diphenyl oxide may be continu- When,therefore,the thiohydrolytic operation ouslv returned to the initial stage, thus main is to-beconducted in the presence of'water, it taining within the system a substantially conis necessary to take the coexistent hydrolytic stant quantity of those compounds which will action into consideration. not beincreased by any further formation E111 the practice of this invention it is posthereof from the reacting substances. The .sible to. drive the thiohydrolytic operation maximun yield of primary products -will entirely to reduction of a mercaptan, and in accordingly be attained, without loss due to similar fashion the simultaneous hydrolytic the formation of secondaryproducts. operation is limited to the production of an Other modes of applying the principle of alcohol. The production of a certain my invention may be employed instead of :amount of alcohol by hydrolysis due to the those explained, change being made as represence of water cannot be entirelypregards the process herein disclosed,provided vented, although it may .becontrolled by the means stated by any of the following r g lating the concentrationof the inorganic claims or the equivalent of such stated means reaction components furnishing the sulph- 'be employed,

hydric "and hydroxide radicals 01' ions- I therefore particularly point outa-nd dis- When' thiohydrolysis is to be carried out in an tinctly claim as my invention aqueous medium it is, therefore,required that 1. In aprocess for the manufacture of a -suehproportional quantities of organic sul- .thiohvdroxy compound, the step which con- :phide together with organic oxide as are each sists in reacting between hydrogen sulphide capable 0f formation under the conditions Of and a, ,monohalogennterl hydroc arbon while "the-reaction shallbeconjointlyintroducedinto v including the corresponding thioether with .tbe system in order to maintain the latter in th ti i di nt 5o -an approximate state OI blltUlCOfiS atlects Hi8 In ux Dq-OQQs for. the n anufacture of a concentration of primary products, mercapthiohvdroxv'compound, the step which contanand alcohol, on the one'hand and secsisfg in reahting between hydrogen sulphide oud ry derivatives, sulphide and oxide, on and a monohalogenated hydrocarbon while ,the other. Thiohydrolvtic opera i in including the corresponding thioether with r55 aqueous media-arethereby directed substanth ti infn'grlignts i t ffi i t tiallyto production of mercaptans, together t i t i th System i an approximate .with whatever proportionalamount of alcot t f h i l b l ith respect hols cannot be ravoideddue to the presence th t of water. p 3. In a process for the manufacture of a p A mlxtllre'of 0119 171019 thiohvdroxy compound, the steps which conibenzenevand'slightlymorethan 2 moles of gist i reaetingbetween hydrogen sulphide 1m alkali metal sulphhydrate, or correspondand a monohalogenated hydrocarbon. sepaing equivalent of an alkaline earth metal rating the thiohydroxy compound formed :sulphhyrlrate. in concentrated aqueoussolufrom the accompanying thioether, and re- 'tion is placed in a suitable enclosed'vessel or turning the latter .to the initial reaction.

4. In" a process for the manufacture of a thiohydroxy compound, the step which consists in reacting between hydrogen sulphide and a monohalogenated hydrocarbon in a medium consisting of an aqueous solution of an alkali or alkaline-earth metal sulphhyclrate while including the corresponding thioether and organic oxide with the reacting ingredients.

5. In a process for the manufacture of a thiohydroxy compound, the step which consists in reacting between hydrogen sulphide and a monohalogenated hydrocarbon in a medium consisting of anaqueous solution of an alkali or alkaline-earth metal sulphhydrate While including the corresponding thioether and organic oxide with the reacting ingredients in amount sufficient to maintain the system in an approximate state of chem- I WILLIAM J. HALE. 

